Sudden Death Syndrome (SDS) is an important soybean disease that causes root rot, defoliation, and yield loss. This disease is caused by the soilborne fungus Fusarium viguliforme that infects the roots and produces a toxin responsible for the foliar symptoms. SDS is extremely variable and 
hard to predict in field conditions, so disease management is a major challenge for growers. The goal of my research is to better understand the factors that cause variability in SDS symptom expression in order to improve disease management. My research addresses questions about the possible sources of variability at different stages of the disease cycle, including: what pathogen levels are needed in soil for disease development; what is the importance of timing of root infection on disease severity; what kind of interaction is there between SDS and other root rot 
pathogens, particularly the soybean cyst nematode; how do post-infection environmental factors affect symptom expression; and what level of genetic variability is present in pathogen populations and how does it affect aggressiveness on soybeans?